Blackface Preamp with Tonemender Stack

[Neil mcNasty]

For Royboy:
Let me know if you run across any problems...

Note that I have done a slight modification, based on reports about the circuit:
I did not include a Volume pot after the Tone-Stack, and instead I added a "master" volume control at the output.

[nocentelli]

Have you got a link to the schematic you used for this?

[Neil mcNasty]

I used the perfoboard supplied by Royboy in this thread: http://guitar-fx-layouts.42897.x6.nabble.com/Preamp-jc-120-td39378.html
+ the info I found in the Instructables article he refers to...

[H.A.M]

Nice one!

Solid-state Fender Blackface Preamp: http://www.redcircuits.com/Page120.htm
ROG Tonemender: http://www.runoffgroove.com/tonemender.html

[Royboy]

Thank you very much Neil.I have been trying to put it ontovero board again in the last few days but have not succeeded.  I have been also trying to build The Morley JD 10 from Sabrotone but have put it on hold till I finish this one.
I also bought the pcb of the Lab series Preamp from Aion Electronics.It is a big project and I am having trouble finding some of the parts so it is on hold too

Thank you again for your trouble

[kuzieem]

Has anyone build this yet? I'm getting heavy distorted sound (built without the switches). Any tips?

[holm]

Cool, thanks for sharing, gotta build this for sure.

So there is no gain control is that correct? Which of the listed transistors would you use for low gain?

\Erik

[kuzieem]

śr., 9.05.2018, 10:38 użytkownik holm [via Guitar FX Layouts] <[hidden email]> napisał:

Cool, thanks for sharing, gotta build this for sure.

So there is no gain control is that correct? Which of the listed transistors would you use for low gain?

\Erik

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NAML

[kuzieem]

śr., 9.05.2018, 10:38 użytkownik holm [via Guitar FX Layouts] <[hidden email]> napisał:

Cool, thanks for sharing, gotta build this for sure.

So there is no gain control is that correct? Which of the listed transistors would you use for low gain?

\Erik

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NAML

[holm]

Ok, thanks, I'm not the right person to ask wrt debugging, but you'd wanna post it in the debugging section. Guess I'll wait and see you get your issues sorted out.

\Erik

[doxasound]

This one is verified!

Like someone else here mentioned, there's a lot of distortion/gain that you cannot decrease with just this layout.

Like the original, you have to add a 1Ma pot after the treble pot (wire the "gain" pot as a typical volume pot between Treble 2 and the board). After that you can decrease the gain.

For my use, it still doesn't get as clean as I want it to.

To fix this I tried putting a volume pot at the input to decrease the signal clipping the jfets, but that affects your unity gain with other pedal. It also affects the noise floor of the circuit. For example, lower input signal means higher output signal, means a bit more white noise since the output volume is so high.

[tacromx]

In theory, lowering the resistor values to say 47K (the two left of Q2 and the two to the right of Q4) wil give you a much cleaner signal. You could even replace them with two dual gang A50K pots giving you pre and post EQ gain.

Just a thought.